My brother has been Coeliac for the past 7 years and diabetic for 15 years. For the past 5+ yrs he has suffered depression. He has seen many specialists, taken many things and even had ECT, the specialists have always said his depression was related to him not coping with having coeliac or life events ie break up of a relationship. He has always maintained this is not the cause. Just recently we believe we have worked out he gets depressed when he has eaten gluten and up until now that seems to have been the case, however, on Sunday he became depressed when he was certain he had not eaten gluten. The depression lasted to Tuesday, then he was back to his positive self. So has anyone else experienced brief depression for no obvious reason?

All I can think is if he is just recently learning that gluten affects him, maybe he still has it around and just hasn't put the puzzle together.

I have almost all neurological symptoms. Crazy mood swings, irritability, and depression along with stomach cramps (which are helpful in hindsight to know what must've had gluten in it.). For example, shredded cheese from the store has gluten in it... it is dusted with flour. Imitation crabmeat has gluten in it. My foundation has gluten in it and was causing itchy patches all over my face. I am mentioning these things because until your brother decides to get serious in discovering what is causing his reaction, he won't pay attention enough. Does that make sense? You really have to become a detective about it!
I am still learning. Sometimes the hard way....today I am going through a reaction from some granola I forgot had gluten in it.
The feelings of depression are hopelessness, sadness, and feeling like everything runs in circles. If I'm washing the dishes I am thinking it will never end... If I'm doing laundry, it is a neverending cycle. Things like that.

I hope this helps you. I noticed no one else posted, but thought it might help to hear what the depression part of it is like. I know mine will probably go away tomorrow. I have to keep reassuring myself that it is just for a time, and I will feel better again.

Apologies in advance because my posts always appear rather random, (was looking for a cross-eyed smiley), but here goes anyway.
Back when eating gluten one of the things I used to get was tearful. This would always be after being in a coffee shop (having had a teacake or scone) or after lunch (sandwich) or very noticeably, after porridge or oats. I'm talking within ten minutes. I'd like to add that I am in fact a very happy bunny underneath. I refer to this as a specific symptom that I used to notice rather than major depression, anxiety, etc that I have also had. To this day I maintain that oats make me cry!

Having to go gluten free and of course, other life events understandably give problems but I would certainly consider ongoing depression and mood swings as evidence of underlying cc or other problem foods.